Email is transmitted across the Internet using the Simple Mail Transport Protocol.

STARTTLS is an SMTP command that allows the client to upgrade an existing insecure connection to a secure, encrypted TLS connection. It is widely supported by SMTP servers and used to protect email transmissions from interception.

Reference – CEH v13 Official Study Guide:

Module 20: Cryptography

Section: Secure Email Communication

Quote:

“STARTTLS is an SMTP command used to initiate encryption on an existing plaintext connection using TLS.”

Incorrect Options:

A. Opportunistic TLS is a concept, not a command

B & C. UPGRADETLS and FORCETLS are not valid SMTP commands